Formula 1
W = 2.75k (T-t) W/m
E .log 10 (D/d)
Where ;
- W= watts /metre heat input required
- k= thermal conductivity of insulation material watts/m C
- T= temperature to be maintained C
- t=ambient temperature C
- D= diameter across insulation
- d = outside diameter of pipe
- E= efficiency factor , use 0.73 but may vary
In the majority of cases, it’s more economical to maintain the heating over short shutdown periods, e.g. weekends than to make provision for heating up from cold. Where its essentials to provide sufficient heat for warming up in addition to heat loss compensation, the time allowed for warming up should be 12-24 hours, as shorter periods normally involve inconveniently high loadings.
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